JPH0925507A - Method for refining molten steel - Google Patents
Method for refining molten steelInfo
- Publication number
- JPH0925507A JPH0925507A JP17352695A JP17352695A JPH0925507A JP H0925507 A JPH0925507 A JP H0925507A JP 17352695 A JP17352695 A JP 17352695A JP 17352695 A JP17352695 A JP 17352695A JP H0925507 A JPH0925507 A JP H0925507A
- Authority
- JP
- Japan
- Prior art keywords
- slag
- molten steel
- refining
- ladle
- steel
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Landscapes
- Treatment Of Steel In Its Molten State (AREA)
Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明は溶鋼の炉外精錬に係
り、とくに精錬容器に混入したスラグを迅速かつ経済的
に改質して、アルミキルド極低炭素鋼の清浄性を向上さ
せる溶鋼の精錬方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the out-of-pile refining of molten steel, and in particular, the refining of molten steel for improving the cleanliness of aluminum-killed ultra-low carbon steel by rapidly and economically modifying the slag mixed in the refining vessel. Regarding the method.
【0002】[0002]
【従来の技術】アルミキルド極低炭素鋼の製造に当って
は、炭素含有量が数10ppm以下の極低炭素域である
ことは当然のことながら、鋼板の使用上での曲げ加工等
から高い清浄性が要求されている。2. Description of the Related Art In the production of aluminum-killed ultra-low carbon steel, it is natural that the carbon content is in the ultra-low carbon range of several tens of ppm or less, but it is highly clean due to bending during use of the steel sheet. Sex is required.
【0003】従来から溶鋼の清浄性とスラグの酸化度と
の関係が明らかにされており、スラグの全酸化鉄量(以
下、(T.Fe)という)を低下させるほど溶鋼中全酸
素量(以下、(T.O)という)は低減する。そこで、
溶鋼の清浄性を向上させるためにスラグの(T.Fe)
を低減する操作として所謂スラグ改質が行なわれてい
る。従来から下記に示す種々の精錬方法が提案されてい
る。The relationship between the cleanliness of molten steel and the degree of oxidation of slag has heretofore been clarified, and the total amount of iron oxide in molten steel (hereinafter referred to as (T.Fe)) decreases as the total iron oxide content of the slag (hereinafter referred to as (T.Fe)) decreases. Hereinafter, (TO) will be reduced. Therefore,
To improve the cleanliness of molten steel, the slag (T.Fe)
So-called slag reforming is carried out as an operation for reducing the above. Conventionally, various refining methods shown below have been proposed.
【0004】特開昭59−70710号公報には、製鋼
炉から取鍋へ出鋼した溶鋼を真空2次精錬するに際し、
製鋼炉からの出鋼時に製品としてほぼ必要量の脱酸剤を
添加すると共に、脱酸生成物の合体浮上促進のためのフ
ラックスを添加するか、もしくはその後更に酸化性スラ
グを改質するためにスラグ還元剤を併用添加する高清浄
鋼の製造方法(第1法)が開示されている。In Japanese Patent Laid-Open No. 59-70710, when the molten steel discharged from a steelmaking furnace to a ladle is secondarily smelted in a vacuum,
In order to add almost the required amount of deoxidizer as a product at the time of tapping steel from the steelmaking furnace, and to add a flux for promoting coalescence floating of the deoxidized product, or to further modify the oxidizing slag after that. A method (first method) for producing highly clean steel in which a slag reducing agent is added together is disclosed.
【0005】また、特開平6−256836号公報に
は、RH脱ガス炉での真空脱炭処理が終了した後に、真
空槽内への溶鋼の吸い上げを一時中断し、取鍋内スラグ
にアルミニウム等の還元剤を添加する方法(第2法)が
開示されている。Further, in Japanese Unexamined Patent Publication No. 6-256836, after the vacuum decarburization treatment in the RH degassing furnace is completed, the sucking of the molten steel into the vacuum chamber is temporarily stopped, and the slag in the ladle is made of aluminum or the like. The method (second method) of adding the reducing agent is disclosed.
【0006】また、特開平3−294414号公報に
は、精錬容器内の溶鋼上に浮遊している酸化性スラグに
対する還元材の存在下で、不活性ガスプラズマを上方か
ら照射して酸化性スラグを還元改質するに際し、酸化性
スラグの塩基度を2以上に調整するとともに、還元剤と
して溶鋼中に溶解したアルミニウムを利用して、このア
ルミニウムを溶鋼の最終目標成分濃度以上で酸化性スラ
グを還元するに充分な量を事前あるいは精錬中に含有さ
せ、不活性ガスプラズマ照射を行なうと共に、溶鋼のガ
ス攪拌を行なう方法(第3法)が開示されている。Further, in Japanese Patent Laid-Open No. 3-294414, the oxidizing slag is irradiated from above with an inert gas plasma in the presence of a reducing agent for the oxidizing slag floating on the molten steel in the refining vessel. When reducing and reforming, the basicity of the oxidizing slag is adjusted to 2 or more, and aluminum dissolved in molten steel is used as a reducing agent to convert the oxidizing slag to the final target component concentration of molten steel or higher. A method (third method) in which an amount sufficient for reduction is contained in advance or during refining, irradiation with an inert gas plasma and gas stirring of molten steel are disclosed.
【0007】[0007]
【発明が解決しようとする課題】しかしながら、これら
の従来技術は、いずれも様々な問題点を抱えている。例
えば第1法は、第1にスラグ還元剤の添加が不足する場
合は(T.Fe)の低減が不十分に終わってしまう、第
2にスラグ還元剤の添加によりスラグの融点が上昇して
スラグが固化するため、スラグのAl2 O3 吸収能が低
下し、溶鋼清浄性が低下する、第3に取鍋上方から添加
されたスラグ還元剤は溶鋼中酸素と反応して、真空2次
精錬開始時に脱炭のための溶鋼中酸素が不足し、脱炭時
間の延長や、脱炭不良の原因となる。とくに還元剤の過
剰添加は脱炭不可能となる場合もある。However, all of these conventional techniques have various problems. For example, in the first method, firstly, when the addition of the slag reducing agent is insufficient, the reduction of (T.Fe) ends up insufficiently, and secondly, the addition of the slag reducing agent increases the melting point of the slag. Since the slag solidifies, the Al 2 O 3 absorption capacity of the slag decreases, and the molten steel cleanliness decreases. Thirdly, the slag reducing agent added from above the ladle reacts with oxygen in the molten steel to produce a secondary vacuum. Oxygen in molten steel for decarburization is insufficient at the start of refining, which causes extension of decarburization time and decarburization failure. In particular, excessive addition of a reducing agent may make it impossible to decarburize.
【0008】また第2法は、真空脱炭処理後にスラグ改
質を行なってはいるが、RH脱ガス処理を一時中断しな
ければならず、復圧工程、取鍋下降工程、スラグ改質工
程、取鍋上昇工程、減圧工程と少なくとも5つの工程を
経る必要があり、生産性は決して高いとは言えない。ま
た、RH脱炭処理を一時中断した後、取鍋上方からスラ
グ還元剤を投入するため、外気との接触によりスラグ還
元剤の酸化ロスも考えられる。In the second method, although the slag reforming is performed after the vacuum decarburizing treatment, the RH degassing treatment must be temporarily interrupted, and the recompression process, the ladle lowering process, and the slag reforming process are required. It is necessary to go through at least 5 steps of ladle raising process and depressurizing process, and productivity cannot be said to be high. Further, after the RH decarburization treatment is temporarily interrupted, the slag reducing agent is introduced from above the ladle, so that the slag reducing agent may be lost due to contact with the outside air.
【0009】さらに第3法は、溶鋼中に存在するアルミ
ニウムなどの脱酸元素を用いてスラグ改質を行なっては
いるが、スラグを溶解するために不活性ガスプラズマを
用いなければならず、設備及びエネルギーコストが増大
するばかりでなく、スラグを高温にするため取鍋耐火物
の溶損が著しくなり、耐火物コストが増大する。Further, in the third method, although slag reforming is performed by using a deoxidizing element such as aluminum present in molten steel, an inert gas plasma must be used to dissolve the slag, Not only the equipment and energy costs increase, but also the melting temperature of the slag increases, so that the melting loss of the ladle refractory becomes significant and the refractory cost increases.
【0010】本発明の目的とするところは、転炉から出
鋼された溶鋼の2次精錬工程において、取鍋スラグの
(T.Fe)を低減するとともに、取鍋スラグのAl2
O3 吸収能を向上させ、さらに効果的に高清浄アルミキ
ルド極低炭素鋼を溶製することができる溶鋼の精錬方法
を提供する。The object of the present invention is to reduce (T.Fe) of ladle slag in the secondary refining process of molten steel discharged from a converter and to increase Al 2 of the ladle slag.
(EN) A refining method for molten steel capable of improving O 3 absorption capacity and more effectively producing highly clean aluminum killed ultra low carbon steel.
【0011】[0011]
【課題を解決するための手段】本発明に係る溶鋼の精錬
方法は、精錬炉で粗脱炭した溶鋼を取鍋に出鋼した後
に、該取鍋内溶鋼をRH脱ガス設備で真空脱炭する溶鋼
の精錬方法において、出鋼中に焼石灰を添加してスラグ
の融点を下げ、次いで未脱酸状態の溶鋼をRH脱ガス設
備で真空脱炭し、さらにアルミニウム脱酸を行なった後
に、該溶鋼を溶鋼攪拌機能と合金添加機能を備えた別の
簡易精錬設備にてスラグと溶鋼が充分攪拌されるように
精錬して、溶鋼の成分調整とスラグ改質を同時に行なう
ことを特徴とする。A method for refining molten steel according to the present invention is such that molten steel that has been roughly decarburized in a refining furnace is tapped into a ladle, and then the molten steel in the ladle is vacuum decarburized by an RH degassing facility. In the method for refining molten steel, the melting point of slag is lowered by adding burnt lime to the tapped steel, then the undeoxidized molten steel is vacuum decarburized by the RH degassing equipment, and aluminum deoxidation is further performed. It is characterized in that the molten steel is refined in another simple refining equipment having a molten steel stirring function and an alloy addition function so that the slag and the molten steel are sufficiently stirred, and the composition adjustment of the molten steel and the slag reforming are simultaneously performed. .
【0012】なお、スラグ改質中およびスラグ改質後の
取鍋スラグの組成が、塩基度CaO/SiO2 が5±
0.2の範囲となり、かつ、CaO/Al2 O3 が1.
5±0.1の範囲となるように、予め出鋼中に焼石灰を
投入することが好ましい。The composition of the ladle slag during and after slag reforming is such that the basicity CaO / SiO 2 is 5 ±.
The range is 0.2 and CaO / Al 2 O 3 is 1.
It is preferable to add burned lime to the tapped steel in advance so that the range is 5 ± 0.1.
【0013】本発明は次の5つの特徴を有する。第1
に、溶鋼攪拌と合金投入機能のみを有する安価で建造可
能な設備にてスラグ改質と成分調整を同時に行なうこ
と、第2に、RH脱ガス機能を上記設備へ一部分化する
ことにより低コストで生産性を向上できること、第3
に、RH脱炭精錬の後でスラグ改質を行なうことにより
RH脱炭処理が溶鋼中[O]濃度低下の影響を受けるこ
とが無く効率的に行なわれること、第4に、溶鋼中のA
lとスラグの攪拌によりスラグ改質を行なうので、Al
反応効率とスラグ改質の均一性の向上が可能になるこ
と、第5に、予めスラグ改質処理中の溶鋼温度でスラグ
が溶解するように転炉で焼石灰を投入しておくため、プ
ラズマやアークといったスラグ溶解のための加熱設備を
必要としないこと、である。The present invention has the following five features. First
At the same time, the slag reforming and the composition adjustment can be performed at the same time in the equipment that can be constructed at a low cost and has only the molten steel stirring and alloy feeding functions. Being able to improve productivity, third
In addition, by performing slag reforming after RH decarburization refining, the RH decarburization treatment can be efficiently performed without being affected by the decrease in [O] concentration in the molten steel.
Since slag modification is performed by stirring 1 and slag,
It is possible to improve the reaction efficiency and the uniformity of slag reforming. Fifthly, since the burnt lime is charged in the converter in advance so that the slag is melted at the molten steel temperature during the slag reforming treatment, the plasma That is, it does not require heating equipment for melting slag such as arc and arc.
【0014】[0014]
【発明の実施の形態】以下、添付の図面を参照しながら
本発明の実施の形態について説明する。図1に示すよう
に、簡易精錬設備の溶鋼収納容器として取鍋4が製鋼工
程において用いられる。取鍋4のなかには溶鋼2及びス
ラグ3が収容されている。ガス吹込み用ランス10の吹
込み口10aが取鍋内溶鋼2に浸漬され、溶鋼2及びス
ラグ3がガス攪拌されるようになっている。ガス吹込み
用ランス10には流量制御弁を備えたガス供給源(図示
せず)から配管11を介してアルゴンガス及び窒素ガス
が供給されるようになっている。BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. As shown in FIG. 1, a ladle 4 is used in a steelmaking process as a molten steel storage container of a simple refining equipment. Molten steel 2 and slag 3 are housed in the ladle 4. The injection port 10a of the gas injection lance 10 is immersed in the molten steel 2 in the ladle so that the molten steel 2 and the slag 3 are gas-stirred. Argon gas and nitrogen gas are supplied to the gas injection lance 10 from a gas supply source (not shown) equipped with a flow rate control valve through a pipe 11.
【0015】また、サブランス13の測定部12が溶鋼
2及びスラグ3のなかに浸漬されている。サブランス1
3の測定部12は溶鋼及びスラグの温度測定、溶鋼中酸
素濃度の測定及びサンプリングに用いられる。なお、各
ランス10,13は昇降装置(図示せず)によってそれ
ぞれ昇降可能に支持されている。The measuring portion 12 of the sublance 13 is immersed in the molten steel 2 and the slag 3. Sublance 1
The measuring unit 12 of No. 3 is used for measuring the temperature of molten steel and slag, measuring the oxygen concentration in molten steel, and sampling. The lances 10 and 13 are supported by an elevating device (not shown) so that they can be moved up and down.
【0016】本実施例では取鍋4に上蓋5を被せてある
程度の気密性を保っている。ガス吹込み用ランス10及
びサブランス13は上蓋5の挿通孔を介して取鍋4内に
装入されている。溶鋼から供給される熱と溶鋼中のアル
ミニウムおよびガス攪拌により、取鍋内スラグ中の酸化
物(鉄やマンガンなどの酸化物)の還元反応を進行させ
る。加えてガス攪拌による介在物の凝集合体と浮上促進
効果により、溶鋼の清浄性向上を達成させるようになっ
ている。In this embodiment, the ladle 4 is covered with the upper lid 5 to maintain airtightness to some extent. The gas blowing lance 10 and the sub lance 13 are inserted into the ladle 4 through the insertion hole of the upper lid 5. The reduction reaction of oxides (oxides such as iron and manganese) in the slag in the ladle is promoted by the heat supplied from the molten steel and the agitation of aluminum and gas in the molten steel. In addition, the cleanliness of molten steel is improved by the agglomeration of inclusions by gas agitation and the effect of promoting floating.
【0017】また、取鍋4の上方には複数のホッパ7が
設けられ、秤量機8で秤量した所定量の合金及びフラッ
クス等の副原料がホッパ7からシュータ9を通って取鍋
4内に投入されるようになっている。Further, a plurality of hoppers 7 are provided above the ladle 4, and predetermined amounts of auxiliary materials such as alloy and flux weighed by the weighing machine 8 pass through the shooters 9 from the hopper 7 into the ladle 4. It is supposed to be thrown in.
【0018】次に、図2、図3、表1、表2を参照しな
がら生産性、スラグ組成ならびにスラグ改質につき実施
例の方法を比較例の方法と比べて説明する。図2は本発
明の実施例に係る方法を用いて溶鋼を精錬する場合のタ
イムチャートを示し、図3は比較例の方法(従来の方
法)を用いて溶鋼を精錬する場合のタイムチャートを示
す。Next, with reference to FIGS. 2 and 3, Tables 1 and 2, the method of the embodiment will be described in comparison with the method of the comparative example in terms of productivity, slag composition and slag reforming. 2 shows a time chart when refining molten steel using the method according to the embodiment of the present invention, and FIG. 3 shows a time chart when refining molten steel using the method of the comparative example (conventional method). .
【0019】先ず生産性について両者を比較する。本発
明者らは、転炉製鋼時間30分(=T1 ),RH脱ガス
精錬時間40分(=T2 )(その内訳は真空脱炭に18
分,脱酸及び成分調整に10分,処理準備時間に12
分)からなる極低炭素鋼の多連鋳の精錬プロセスにおい
て、RH脱ガス精錬では真空脱炭とアルミニウムの投入
による溶鋼脱酸のみを行ない、成分調整は別設備で行な
った場合の取鍋運行をシミュレーションした。その結果
を図2に示した。図から明らかなようにCC鋳造設備に
おける第1ヒートから第5ヒートまでの出鋼から鋳造ま
での時間にあたるリードタイムはそれぞれ85分となっ
た。First, the two are compared in terms of productivity. The present inventors have found that the converter steelmaking time is 30 minutes (= T 1 ) and the RH degassing refining time is 40 minutes (= T 2 ).
Minutes, 10 minutes for deoxidation and component adjustment, 12 for treatment preparation time
In the refining process of continuous casting of ultra-low carbon steel consisting of (1)), RH degassing refining performs only vacuum decarburization and molten steel deoxidation by inputting aluminum, and ladle operation when component adjustment is performed in another facility Was simulated. The result is shown in FIG. As is clear from the figure, the lead time corresponding to the time from tapping to casting in the first heat to the fifth heat in the CC casting facility was 85 minutes.
【0020】ここで、各プロセス間の移動に要する時間
の内訳は、転炉からRH脱ガス設備までが約20分、R
H脱ガス設備から簡易取鍋精錬設備までが約5分、RH
脱ガス設備からCC鋳造設備までが約20分、簡易取鍋
精錬設備からCC鋳造設備までが約20分である。転炉
製鋼時間をT1 、RH脱ガス精錬時間をT2 、簡易取鍋
精錬時間をT3 とそれぞれおくと、転炉製鋼時間T1 と
それ以降の精錬処理ピッチ時間T2 ,T3 …とは下式
(1)の関係にある。Here, the breakdown of the time required for transfer between processes is about 20 minutes from the converter to the RH degassing equipment, and R
About 5 minutes from H degassing equipment to simple ladle refining equipment, RH
It takes about 20 minutes from the degassing equipment to the CC casting equipment and about 20 minutes from the simple ladle refining equipment to the CC casting equipment. When the converter steelmaking time is T 1 , the RH degassing and refining time is T 2 , and the simple ladle refining time is T 3 , respectively, the converter steelmaking time T 1 and the refining process pitch times T 2 and T 3 thereafter ... And have the relationship of the following formula (1).
【0021】T1 ≧T2 ,T3 … …(1) 一方、従来の方法においては図3から明らかなように、
転炉製鋼時間T1 が30分、RH脱ガス精錬時間T2 が
40分と同じであるが、CC鋳造設備における各ヒート
ごとのリードタイムはそれぞれ120分(第1ヒー
ト)、110分(第2ヒート)、100分(第3ヒー
ト)、90分(第4ヒート)、80分(第5ヒート)と
なった。T 1 ≧ T 2 , T 3 (1) On the other hand, in the conventional method, as is clear from FIG.
The converter steelmaking time T 1 is the same as 30 minutes and the RH degassing refining time T 2 is 40 minutes, but the lead times for each heat in the CC casting equipment are 120 minutes (first heat) and 110 minutes (first heat), respectively. 2 heats), 100 minutes (3rd heat), 90 minutes (4th heat), and 80 minutes (5th heat).
【0022】これにより本実施例の方法によれば1ヒー
ト当たりの平均リードタイムが従来の方法よりも大幅に
短縮されることを見出した。なお、このシミュレーショ
ンにはスラグ改質ポジションをRH脱ガス処理後に変更
することによって、RH脱炭精錬がスラグ改質の影響を
受けなくなることによるRH脱炭時間の短縮を3分間程
度と見込んでいる。この結果、極低炭素鋼のRH脱ガス
処理では、真空脱炭処理とアルミニウムなどによる脱酸
のみを行ない、成分調整は溶鋼攪拌機能と合金鉄投入機
能を具備するガスバブリング設備において行なうことと
した。As a result, it has been found that the method of this embodiment significantly reduces the average lead time per heat as compared with the conventional method. In this simulation, the RH decarburization time is expected to be shortened to about 3 minutes by changing the slag reforming position after the RH degassing treatment so that the RH decarburization refining is not affected by the slag reforming. . As a result, in the RH degassing treatment of ultra-low carbon steel, only vacuum decarburization treatment and deoxidation with aluminum etc. were performed, and the composition adjustment was carried out in a gas bubbling facility equipped with a molten steel stirring function and a ferroalloy charging function. .
【0023】ここで真空脱炭処理をRH脱ガス設備で行
なう理由は真空処理が必要不可欠だからであり、また、
RH脱ガス設備で溶鋼の脱酸処理まで行なう理由は可及
的速やかに脱酸するほうが溶鋼の温度降下が小さく、か
つ耐火物の溶損が少なくなるからである。さらに、成分
調整をガスバブリング設備で行なう理由は、成分調整に
ついては攪拌機能さえ備えていれば、極低炭素鋼の場合
はことさらに真空処理を必要としないからである。なお
上述のガスバブリング設備は、連鋳前の溶鋼成分の均一
化及び温度の均一化を図るために通常はCC鋳造設備の
直前に設置されているものであり、物流の妨げにならな
いことは言うまでもなく、既設のものに若干の改造を加
えるなどして安価に設置することも可能になるからであ
る。The reason why the vacuum decarburization process is performed in the RH degassing facility is that the vacuum process is indispensable.
The reason for performing deoxidation treatment of molten steel in the RH degassing facility is that deoxidation as quickly as possible causes a smaller temperature drop of molten steel and less melting loss of refractory. Furthermore, the reason why the components are adjusted in the gas bubbling facility is that the ultra-low carbon steel does not require further vacuum treatment as long as it has a stirring function for the components adjustment. The above-mentioned gas bubbling equipment is usually installed immediately before the CC casting equipment in order to equalize the molten steel composition and the temperature before continuous casting, and it goes without saying that it does not hinder logistics. It is also possible to install it at low cost by modifying the existing one.
【0024】次にスラグの組成について説明する。取鍋
スラグの重要な役割の一つに溶鋼中介在物の吸収がある
が、これにはスラグが溶融状態であり流動性の高い状態
であることが必要になる。一方、スラグ中の有害酸化物
(鉄やマンガンの酸化物)の濃度を低減するとともにそ
の活量を下げるには、スラグの塩基度(CaO/SiO
2 )を高くする必要がある。しかし、スラグの塩基度が
高くなり過ぎると、スラグは石灰の物性に近づくため
に、スラグ融点が上昇してスラグの流動性が損なわれ、
スラグのAl2 O3 吸収能が劣化する。Next, the composition of the slag will be described. One of the important roles of ladle slag is the absorption of inclusions in molten steel, but this requires that the slag be in a molten state and highly fluid. On the other hand, in order to reduce the concentration of harmful oxides (oxides of iron and manganese) in the slag and reduce its activity, the basicity of the slag (CaO / SiO 2
2 ) Need to be higher. However, if the basicity of the slag becomes too high, the slag approaches the physical properties of lime, so the melting point of the slag rises and the fluidity of the slag is impaired,
The Al 2 O 3 absorption capacity of the slag deteriorates.
【0025】以上のことから、スラグをプラズマやアー
クなどによって加熱することなく、溶鋼の保有熱のみで
スラグを溶融状態とするためには、塩基度だけでなく、
その他のスラグ中酸化物組成についても考慮する必要が
ある。本実施例では、RH脱ガス処理後の溶鋼温度が1
600℃となる条件下でスラグを溶融状態とするべく、
CaO−SiO2 −Al2 O3 の3元系状態図より塩基
度CaO/SiO2 を約5とし、かつCaO/Al2 O
3 を約1.5に規定したものをスラグ改質中およびスラ
グ改質後のスラグ組成とした。From the above, in order to bring the slag into a molten state only by the heat retained by the molten steel without heating the slag by plasma or arc, etc.
It is also necessary to consider other oxide compositions in slag. In this example, the molten steel temperature after the RH degassing treatment was 1
To make the slag molten under the condition of 600 ° C,
CaO-SiO 2 -Al basicity CaO / SiO 2 from ternary phase diagram of the 2 O 3 and approximately 5, and CaO / Al 2 O
The slag composition during and after slag reforming was defined as 3 to about 1.5.
【0026】次に、スラグ改質に用いる還元剤及びその
供給方法について説明する。本発明はアルミキルド極低
炭素鋼の製造方法に限ったものであり、溶鋼の[C]汚
染を防止するという観点から、還元剤としてAlを使用
する。ところが、スラグ改質処理中に取鍋の上方からA
lを添加すると、添加Alがスラグ上に浮遊し大気との
接触によって酸化消費されて反応効率の低下を招いてし
まう。したがって本発明方法では極力溶鋼中のAlを利
用してスラグと溶鋼の界面反応によりスラグを改質する
ものとした。Next, the reducing agent used for slag reforming and its supply method will be described. The present invention is limited to the method for producing an aluminum-killed ultra low carbon steel, and Al is used as a reducing agent from the viewpoint of preventing [C] contamination of molten steel. However, during the slag reforming process, A
When 1 is added, the added Al floats on the slag and is oxidized and consumed by contact with the atmosphere, resulting in a decrease in reaction efficiency. Therefore, in the method of the present invention, Al in molten steel is used as much as possible to modify the slag by the interfacial reaction between the slag and the molten steel.
【0027】本実施例において、還元剤としてAlを溶
鋼中に含有させる量は、酸化性スラグの改質を充分に行
ない得るとともに、最終目標[Al]を満足する量であ
ることが必要である。このスラグ改質に必要なAl量は
主にスラグ組成とスラグ量とに依存するが、本実施例の
ようにRH脱ガス処理の初期にスラグ組成を分析するこ
とにより概ね正確に見積ることができる。In this embodiment, the amount of Al contained in the molten steel as a reducing agent must be such that the oxidizing slag can be sufficiently modified and the final target [Al] is satisfied. . Although the amount of Al required for this slag reforming mainly depends on the slag composition and the amount of slag, it can be roughly estimated accurately by analyzing the slag composition at the initial stage of the RH degassing treatment as in this example. .
【0028】また本実施例では、転炉出鋼中に焼石灰を
投入するが、これは転炉出鋼流の強力な攪拌力および転
炉出鋼中の高温溶鋼の大きな熱エネルギーを利用して、
添加した石灰の溶融をできるだけ容易にするためのもの
である。In the present embodiment, the burnt lime is introduced into the steel output from the converter, which utilizes the strong stirring power of the steel output from the converter and the large thermal energy of the high temperature molten steel in the steel output from the converter. hand,
This is for facilitating the melting of the added lime as much as possible.
【0029】次に、表1及び表2を参照しながら実施例
の方法を比較例の方法と比べて説明する。表2に示す組
成と同一鋼種の5連々鋳を転炉から出鋼し、本実施例の
方法を比較例としての従来の方法と比べる比較試験を行
なった。Next, the method of the embodiment will be described in comparison with the method of the comparative example with reference to Tables 1 and 2. Five consecutive castings having the same steel type as the composition shown in Table 2 were tapped from the converter, and a comparative test was performed to compare the method of this example with a conventional method as a comparative example.
【0030】本実施例の製造工程は、転炉精錬工程と、
転炉出鋼時焼石灰を添加(1000kg/ヒート)する
工程と、RH脱ガス処理(溶鋼が未脱酸状態での真空脱
炭処理と、その後のAl添加による脱酸処理)工程と、
簡易取鍋精錬処理(主にMnとAlの成分調整とスラグ
と溶鋼の攪拌)工程と、連続鋳造工程とからなる。The manufacturing process of this embodiment includes a converter refining process,
A step of adding burned lime (1000 kg / heat) during tapping of the converter, a RH degassing step (vacuum decarburizing treatment with molten steel in a non-deoxidized state, and a subsequent deoxidizing treatment by adding Al);
It consists of a simple ladle refining process (mainly adjusting Mn and Al components and stirring slag and molten steel) and a continuous casting process.
【0031】比較例の製造工程は、転炉精錬工程と、転
炉出鋼時焼石灰を添加(1000kg/ヒート)する工
程と、出鋼完了後スラグ上にAlを添加(200kg/
ヒート)する工程と、RH脱ガス処理(溶鋼が未脱酸状
態での真空脱炭処理し、その後のAl添加による脱酸処
理と主にMnとAlの成分調整)する工程と、連続鋳造
工程とからなる。The manufacturing process of the comparative example includes a converter refining process, a process of adding burned lime when the converter is tapped (1000 kg / heat), and Al added on the slag after tapping is completed (200 kg /
Heating), RH degassing (vacuum decarburizing with molten steel in a non-deoxidized state, followed by deoxidation by adding Al and mainly adjusting Mn and Al components), and continuous casting step Consists of.
【0032】表1に実施例方法と比較例方法との試験内
容の詳細を併記した。この表1から明らかなように、本
実施例の方法は比較例の方法(従来法)に比べて下記5
つの効果があることが判明した。Table 1 shows the details of the test contents of the example method and the comparative example method. As is clear from Table 1, the method of the present example has the following 5 compared with the method of the comparative example (conventional method).
It turned out to have one effect.
【0033】第1に、ガスバブリングによりスラグと脱
酸元素であるアルミニウムを含んだ溶鋼が反応するた
め、処理後のスラグ中(T.Fe)量は比較例に比べて
低く、スラグの酸化度を大幅に低減することが可能にな
り、その結果タンディッシュ内の溶鋼サンプルの(T.
O)分析値からもわかるように、溶鋼の清浄性が大幅に
向上した。First, since the gas bubbling reacts the slag with the molten steel containing aluminum which is a deoxidizing element, the amount of T.Fe in the slag after the treatment is lower than that of the comparative example, and the oxidation degree of the slag is low. Of the molten steel sample in the tundish (T.
O) As can be seen from the analysis value, the cleanliness of the molten steel was significantly improved.
【0034】第2に、RH処理前の(T.O)量を高い
レベルに保持でき、そのため真空脱炭速度が高く真空脱
炭処理時間が短縮できた。第3に、RH真空処理時間が
短縮され、蒸気原単位が低減した。Secondly, the amount of (TO) before the RH treatment can be maintained at a high level, so that the vacuum decarburization rate is high and the vacuum decarburization treatment time can be shortened. Third, the RH vacuum processing time was shortened and the steam consumption rate was reduced.
【0035】第4に、リードタイムが短く、精錬プロセ
スの生産性を向上させることができた。第5に、プロセ
スのリードタイムが短縮された結果、転炉の出鋼温度を
低減することが可能になり、その結果として炉体寿命が
延び、転炉媒溶剤原単位が低減され、全出鋼歩留りが向
上した。Fourthly, the lead time was short, and the productivity of the refining process could be improved. Fifthly, as a result of shortening the process lead time, it is possible to reduce the steel tapping temperature of the converter, and as a result, the life of the furnace body is extended, the converter solvent solvent unit consumption is reduced, and the total output Steel yield improved.
【0036】加えて全ヒートが同一リードタイムで製造
可能となるため、全ヒート同一プロセスでの精錬(精錬
プロセスの画一化)が可能になり、転炉、RH脱ガス処
理の操業の安定性向上、成分品質の的中率向上の可能性
があることがわかった。In addition, since all heats can be manufactured with the same lead time, refining in the same process for all heats (uniform refining process) becomes possible, and stability of operation of converter and RH degassing process It was found that there is a possibility of improvement and the accuracy rate of the component quality.
【0037】さらに、全ヒートRH脱ガス処理を行なう
ことにより、RH脱ガス設備の稼働率が向上し、RH脱
ガス炉の耐火物が常に高温に保持される結果、耐火物の
寿命が延びる可能性があることも判明した。Further, by performing the full heat RH degassing process, the operating rate of the RH degassing equipment is improved and the refractory of the RH degassing furnace is always kept at a high temperature, so that the life of the refractory can be extended. It turned out that there is a property.
【0038】なお、上記実施例によれば、RH脱ガス処
理の初期に取鍋内に浮遊するスラグを採取し組成を分析
するとともに、取鍋内に浮遊するスラグ厚みを測定し、
この測定値から取鍋内スラグ重量を算出し、これらの分
析値及び算出値からスラグ改質と溶鋼成分調整のための
溶鋼攪拌時間、及びAlの添加量を決定することを追加
するので、さらにAl効率のよい製造方法を提供するこ
とができる。According to the above-mentioned embodiment, the slag floating in the ladle is collected at the initial stage of the RH degassing process to analyze the composition, and the thickness of the slag floating in the ladle is measured.
Since the slag weight in the ladle is calculated from this measured value and the molten steel stirring time for slag reforming and molten steel component adjustment, and the addition amount of Al are determined from these analytical values and calculated values, It is possible to provide a manufacturing method with high Al efficiency.
【0039】[0039]
【表1】 [Table 1]
【0040】[0040]
【表2】 [Table 2]
【0041】[0041]
【発明の効果】以下に、本発明によりもたらされる効果
を列記する。 (1)製鋼工場の生産性を大幅に向上することができ
る。 (2)成分調整処理にガスバブリングを用いることによ
りスラグの酸化度が低減され、溶鋼の清浄性を向上させ
ることができる。 (3)RH脱ガス処理における蒸気の原単位を低減する
ことができる。 (4)転炉出鋼温度を低減することが可能になり、転炉
耐火物の寿命延長、転炉媒溶剤原単位の低減、全出鋼歩
留りの向上が可能になる。 (5)精錬プロセスの画一化が可能になり、成分及び品
質の的中率が向上する。 (6)全ヒートにつきRH脱ガス処理が可能になる結
果、RH脱ガス炉の耐火物が常に高温に保持され、RH
耐火物の寿命が向上する。The effects brought about by the present invention are listed below. (1) It is possible to significantly improve the productivity of a steel factory. (2) By using gas bubbling for the component adjustment treatment, the degree of oxidation of slag is reduced and the cleanliness of molten steel can be improved. (3) The unit consumption of steam in the RH degassing process can be reduced. (4) It is possible to reduce the converter tapping temperature, extend the life of the converter refractory, reduce the converter solvent solvent unit consumption, and improve the total tapping yield. (5) The refining process can be standardized, and the accuracy of the ingredients and quality is improved. (6) As a result of enabling RH degassing treatment for all heat, the refractory of the RH degassing furnace is always kept at a high temperature,
The refractory life is extended.
【図1】本発明の実施例に係る溶鋼の精錬方法に用いら
れた精錬設備を示す概要図である。FIG. 1 is a schematic diagram showing a refining equipment used in a method for refining molten steel according to an embodiment of the present invention.
【図2】本発明の実施例に係る溶鋼の精錬方法によるタ
イムチャートである。FIG. 2 is a time chart of a molten steel refining method according to an embodiment of the present invention.
【図3】従来の方法によるタイムチャートである。FIG. 3 is a time chart according to a conventional method.
4…取鍋、 5…上蓋 7…ホッパ 10…ガス吹込み用ランス、 13…サブランス、 4 ... Ladle, 5 ... Upper lid 7 ... Hopper 10 ... Gas injection lance, 13 ... Sublance,
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 庁内整理番号 FI 技術表示箇所 C21C 7/10 C21C 7/10 A (72)発明者 豊田 剛治 東京都千代田区丸の内一丁目1番2号 日 本鋼管株式会社内─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. 6 Identification number Internal reference number FI Technical indication C21C 7/10 C21C 7/10 A (72) Inventor Gouji Toyota 1-chome, Marunouchi, Chiyoda-ku, Tokyo No. 2 Nihon Steel Pipe Co.
Claims (2)
た後に、該取鍋内溶鋼をRH脱ガス設備で真空脱炭する
溶鋼の精錬方法において、出鋼中に焼石灰を添加してス
ラグの融点を下げ、次いで未脱酸状態の溶鋼をRH脱ガ
ス設備で真空脱炭し、さらにアルミニウム脱酸を行なっ
た後に、該溶鋼を溶鋼攪拌機能と合金添加機能を備えた
別の簡易精錬設備にてスラグと溶鋼が充分攪拌されるよ
うに精錬して、溶鋼の成分調整とスラグ改質を同時に行
なうことを特徴とする溶鋼の精錬方法。1. A method for refining molten steel, in which molten steel roughly decarburized in a refining furnace is tapped in a ladle, and then the molten steel in the ladle is vacuum decarburized in an RH degassing facility. Addition to lower the melting point of slag, then vacuum decarburize the undeoxidized molten steel with RH degassing equipment, and further perform aluminum deoxidation, and then separate the molten steel with a molten steel stirring function and an alloy addition function. The method for refining molten steel is characterized in that the slag and the molten steel are refined in the simple refining equipment so that the molten steel is sufficiently stirred, and the components of the molten steel are adjusted and the slag is reformed at the same time.
スラグの組成が、塩基度CaO/SiO2 が5±0.2
の範囲となり、かつ、CaO/Al2 O3 が1.5±
0.1の範囲となるように、予め出鋼中に焼石灰を投入
することを特徴とする、請求項1記載の溶鋼の精錬方
法。2. The composition of the ladle slag during and after slag reforming is such that the basicity CaO / SiO 2 is 5 ± 0.2.
, And CaO / Al 2 O 3 is 1.5 ±
The method for refining molten steel according to claim 1, wherein burned lime is charged into the tapped steel in advance so as to be in the range of 0.1.
Priority Applications (1)
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---|---|---|---|
JP17352695A JPH0925507A (en) | 1995-07-10 | 1995-07-10 | Method for refining molten steel |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP17352695A JPH0925507A (en) | 1995-07-10 | 1995-07-10 | Method for refining molten steel |
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Publication Number | Publication Date |
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JPH0925507A true JPH0925507A (en) | 1997-01-28 |
Family
ID=15962166
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JP17352695A Pending JPH0925507A (en) | 1995-07-10 | 1995-07-10 | Method for refining molten steel |
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Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR100402005B1 (en) * | 1999-09-10 | 2003-10-17 | 주식회사 포스코 | A METHOD FOR REFINING ULTRA LOW CARBON Al-KILLED STEEL OF HIGH CLEANINESS |
JP2009197285A (en) * | 2008-02-22 | 2009-09-03 | Nippon Steel Corp | Method for producing high clean steel slab |
KR101484947B1 (en) * | 2013-08-30 | 2015-01-21 | 주식회사 포스코 | Method for manufacturing carbon steel |
KR20190076314A (en) * | 2017-12-22 | 2019-07-02 | 주식회사 포스코 | Method for Refining Low Carbon Steel |
WO2020040190A1 (en) * | 2018-08-24 | 2020-02-27 | 日本製鉄株式会社 | Steel material, forged heat-treated article, and method for manufacturing forged heat-treated article |
-
1995
- 1995-07-10 JP JP17352695A patent/JPH0925507A/en active Pending
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR100402005B1 (en) * | 1999-09-10 | 2003-10-17 | 주식회사 포스코 | A METHOD FOR REFINING ULTRA LOW CARBON Al-KILLED STEEL OF HIGH CLEANINESS |
JP2009197285A (en) * | 2008-02-22 | 2009-09-03 | Nippon Steel Corp | Method for producing high clean steel slab |
KR101484947B1 (en) * | 2013-08-30 | 2015-01-21 | 주식회사 포스코 | Method for manufacturing carbon steel |
KR20190076314A (en) * | 2017-12-22 | 2019-07-02 | 주식회사 포스코 | Method for Refining Low Carbon Steel |
WO2020040190A1 (en) * | 2018-08-24 | 2020-02-27 | 日本製鉄株式会社 | Steel material, forged heat-treated article, and method for manufacturing forged heat-treated article |
JPWO2020040190A1 (en) * | 2018-08-24 | 2021-04-08 | 日本製鉄株式会社 | Manufacturing method of steel materials, forged heat-treated products, and forged heat-treated products |
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